How to build a Low Poly on a High Poly while being able to see both?
Lowpoly occluded wire with Highpoly surface


X-Ray disabled
Lowpoly Viewport Display


In Front enabled
Display As Wire





Standard X-Ray with occlusion

The lowpoly wires stay visible even if the surface is not visible.



Notable options to combine:


Overlays > Shading > Hidden Wire
Viewport Shading > Outline (off)